worksheet

1. 1
CHAPTER – 7 : DATABASE
CONCEPTS
M U L TI P L E C H OI C E QU E S T I ON S
1. Repetition of data is called as ?
A) Data Dependency B) Data Redundancy
C) Data Inconsistency D) Data Isolation
2. A is an organized collection of data.
A) Information B) File
C) Database D) DBMS
3. A is a software used to design and maintain databases.
A) Information B) File
C) Database D) DBMS
4. Which of the following is a sketch of design of a planned data?
A) Instance B) Schema
C) Metadata D) Relation
5. Which of the following represents a set of rules that define valid data?
A) Constraint B) Data Dictionary
C) Query D) All of the above
6. A relational database consists of a collection of ?
A) Tables B) Fields
C) Records D) Keys
7. A group of columns serving as a primary key are known as ?
A) Candidate Key B) Alternate Key
C) Composite Key D) Foreign Key
8. Which of the following refers to the data about data?
A) Instance B) Schema
C) Metadata D) Relation
9. The term attribute refers to a of a table
A) Record B) Column
C) Tuple D) Key
10. The term refers to a row of a table.
A) Record B) Column
C) Attribute D) Key
11. The number of attributes in a relation is called as ?
A) size B) degree
C) cardinality D) weight
12. The number of rows in a relation is called as ?
A) size B) degree
C) cardinality D) weight
S HOR T A N S W E R QU E S T ION S
1. Differentiate between:
a) Database state and database schema
b) Primary Key and Foreign Key

2. c) Degree and cardinality of a relation
2. Compared to a file system, how does a database management system avoid redundancy in data through a
database?
3. What are the limitations of file system that can be overcome by a relational DBMS?
4. What is a database system? What is its need?
5. What is a database constraint? Give example.
6. What is a foreign key? What is it used for?
7. What is a query? Give example.
8. What are the three important properties of a relation?
9. Differentiate between Primary Key and Alternate Key.
10. All Candidate Keys are Primary Keys but all Primary Keys are not Candidate Keys. Illustrate the
statement with the help of an example.
L ON G A N S W E R QU E S T I ON S
1. Why foreign keys are allowed to have NULL values? Explain with an example.
2. A school has a rule that each student must participate in a sports activity. So each one should give only
one preference for sports activity. Suppose there are five students in a class, each having a unique roll
number. The class representative has prepared a list of sports preferences as shown below.
Table: Sports Preferences
Roll_no Preference
9 Cricket
13 Football
17 Badminton
17 Football
21 Hockey
24 NULL
NULL Kabaddi
Answer the following:
a) Roll no 24 may not be interested in sports. Can a NULL value be assigned to that
student’s preference field?
b) Roll no 17 has given two preferences sports. Which property of relational DBMC is violated
here? Can we use any constraint or key in the relational DBMS to check against such violation, if
any?
c) Kabaddi was not chosen by any student. Is it possible to have this tuple in the Sports
Preferences relation?
3. In another class having 2 sections, the two respective class representatives have prepared 2 separate
Sports Preferences tables, as shown below:
Sports preference of section 1 (arranged on roll number column)
Table: Sports Preferences
Roll_
no
Sports
9 Cricket
13 Football
17 Badmint
on
21 Hockey
24 Cricket
Sports preference of section 2 (arranged on Sports name column, and column order is also different)
Table: Sports Preferences
Sports Roll_

3. no
Badmint
on
17
Cricket 9
Cricket 24
Football 13
Hockey 21
4. The school canteen wants to maintain records of items available in the school canteen and generate bills
when students purchase any item from the canteen. The school wants to create a canteen database to keep
track of items in the canteen and the items purchased by students. Design a database by answering the
following questions:
a) To store each item name along with its price, what relation should be used? Decide appropriate
attribute names along with their data type. Each item and its price should be stored only once.
What restriction should be used while defining the relation?
b) In order to generate bill, we should know the quantity of an item purchased. Should this
information be in a new relation or a part of the previous relation? If a new relation is required,
decide appropriate name and data type for attributes. Also, identify appropriate primary key and
foreign key so that the following two restrictions are satisfied:
i. The same bill cannot be generated for different orders.
ii. Bill can be generated only for available items in the canteen.
c) The school wants to find out how many calories students intake when they order an item. In
which relation should the attribute ‘calories’ be stored?
5. An organisation wants to create a database EMP-DEPENDENT to maintain following details about its
employees and their dependent.
EMPLOYEE(AadharNumber, Name, Address,
Department,EmployeeID) DEPENDENT(EmployeeID, DependentName,
Relationship)
a) Name the attributes of EMPLOYEE, which can be used as candidate keys.
b) The company wants to retrieve details of dependent of a particular employee. Name the tables
and the key which are required to retrieve this detail.
c) What is the degree of EMPLOYEE and DEPENDENT relation?
6. In a multiplex, movies are screened in different auditoriums. One movie can be shown in more than one
auditorium. In order to maintain the record of movies, the multiplex maintains a relational database
consisting of two relations viz. MOVIE and AUDI respectively as shown below:
Movie(Movie_ID, MovieName, ReleaseDate)
Audi(AudiNo, Movie_ID, Seats, ScreenType, TicketPrice)
a) Is it correct to assign Movie_ID as the primary key in the MOVIE relation? If no, then suggest
an appropriate primary key.
b) Is it correct to assign AudiNo as the primary key in the AUDI relation? If no, then
suggest appropriate primary key.
c) Is there any foreign key in any of these relations?
7. School uniform is available at M/s Sheetal Private Limited. They have maintained SCHOOL_UNIFORM
Database with two relations viz. UNIFORM and COST. The following figure shows database schema
and its state.
a) Can they insert the following tuples to the UNIFORM Relation? Give reasons in support of
your answer.
i. 7, Handkerchief, NULL

4. ii. 4, Ribbon, Red
iii. 8, NULL, White
b) Can they insert the following tuples to the COST Relation? Give reasons in support of your
answer. i. 7, S, 0
ii. 9, XL, 100
8. For the below given database STUDENT-PROJECT, answer the questions that follow
a) Name primary key of each table.
b) Find foreign key(s) in table PROJECT-ASSIGNED.
c) Is there any alternate key in table STUDENT? Give justification for your answer.
d) Can a user assign duplicate value to the field RollNo of STUDENT table? Jusify.
9. For the above given database STUDENT-PROJECT, can we perform the following operations?
a) Insert a student record with missing roll number value.
b) Insert a student record with missing registration number value.
c) Insert a project detail without submission-date.
d) Insert a record with registration ID IP-101-19 and ProjectNo 206 in table
PROJECT-ASSIGNED.